Behind a white door on a graffitied backstreet in Sarajevo, reached by a path that runs past an overgrown garden, sits the registered office of a company that is believed to be on the verge of securing contracts worth more than one billion dollars. AAFS Infrastructure and Energy is reported to be close to winning a concession to build and operate a pipeline across the Balkans, one that would allow liquefied natural gas shipped from the United States to displace supplies that have long been drawn from Russia. "This could be the most important infrastructure project ever in Bosnia and Herzegovina," a senior Bosnian official, who requested anonymity given the sensitivity of ongoing negotiations, has said. What AAFS appears to lack in relevant experience, it is widely considered to compensate for through political proximity to Donald Trump. Among the company's representatives is a Washington lawyer who has acted for the Trump family in political litigation, as well as the brother of the president's former national security adviser. Both individuals are understood to have participated in efforts to contest the outcome of the 2020 presidential election, a cause that has remained close to Trump's priorities. A Guardian investigation, drawing on interviews with current and former officials on both sides of the Atlantic, leaked documents and corporate filings, has sought to examine how an obscure firm came to occupy such a consequential position in the global contest over energy supply. The episode is seen by analysts as illustrative of a broader shift in how American foreign policy is being conducted under an administration that critics argue has struggled to maintain a clear boundary between national interest and private enrichment.…